Asterisk PBX Part 3
Distributions Matter.
The initial experience with Asterisk 1.8.7 on top of the Ubuntu distribution was nothing less than horrific. While the base telephone system functioned, I was having issues with DAHDI, the GUI interface would somehow corrupt underlying configuration files making the PBX unstable and I could not for the life of me get the extensions to recognize an incoming fax using Asterisk Fax. It was painfully apparent that either I did not know what I was doing or there were some tricks to getting this thing to work.
After discussing the issue with some folks in the industry, it became apparent to me that I was going to have to put aside my one linux distribution mentality and add CentOS to the mix. It probably is no big deal to have multiple Linux distributions, but I like keeping things at their lowest common denominator. I have been using Ubuntu for years and I have not touched a Red Hat distribution in nearly the same amount of time. But, I was determined to give Asterisk the full tour and since I was not the expert on Asterisk, I needed to chose a distribution with wide support, especially if this platform were to go into production.
What is interesting is that the Asterisk distributions seem to be concentrated around FreePBX and Asterisk@Home. TrixBox is the spin-off of the Asterisk@Home project started in 2004 and FreePBX is the underpinning of many distributions including Elastix and PBX In A Flash (PIAF). After much ado and grumbling underneath my breath, I selected Elastix as the go to distribution. Elastix had a couple of added features that met the requirements of my unified communications project, it utilized Hylafax to handle nearly all of the fax capabilities, and it had a reasonably informative dashboard that could give you an instant update on the status of the PBX system.
During all of this investigative process, I was not happy to see that Digium had not yet implemented SIP SIMPLE into their software for instant messaging capabilities, and they only announced the capability in their new Version 1.10, now touted as Version 10. It seems every time I need to start a project I am looking at either the deployment of a stable release without the features I desperately need, or the unstable, no clue when it will be stable, use at your own risk version that is just on the event horizon. Tempting as it was, I was in no way going to demonstrate the capabilities of a PBX to a company barely out of the stone age on a beta release. SIP SIMPLE was out for the time being.
I am concerned with Asterisk having to handle the entire load of a corporate telephone infrastructure along with all of the communications required between VoIP users on VPNs and those connected on the local LAN. I am also concerned with having a card inside a server handling the PSTN traffic. How can I have failover? Putting these cards in multiple machines, issues with hardware (interrupts) IRQs, how many different codecs am I going to be dealing with, and how much transcoding is going to be happening? As I begin to evaluate a base Elastix install with a Digium T1/E1 card in the machine, all of these “Oh my God!” moments are welling up inside of me. More research, more Google, and more discussions with vendors, it is time to resolve a number of these questions or we are not going to be able to deploy this system into a production environment and quite possibly replace the enterprise PBX systems. The distribution was now the least of my worries.
Cary H. 
